Generally, methods and apparatus for evaluating or processing hydrocarbon materials having unimodal characteristics which may acquire multimodal characteristics upon processing. Specifically, indica of stability for hydrocarbons having unimodal characteristics which may be used separately, or used in combination, or used in comparison to a determined threshold of instability for such unimodal characteristics, to assist in determining the proximity of hydrocarbon materials having unimodal characteristics to formation of multimodal characteristics, or to assist in pre-determining the degree of acquired multimodal characteristics in response to various processing parameters.
It can be difficult to evaluate, in response to a given set of processing parameters, if, or when, or to what degree, a hydrocarbon material of homogeneous mixture may transition to a hydrocarbon material of heterogeneous mixture to form carbon rich materials, such as coke. When hydrocarbon materials, such as heavy oils, petroleum residua, shale oils, coal tars, tar sand bitumen, asphalts, or the like, are processed at non-pyrolytic temperatures (at or below 340xc2x0 C. or 644xc2x0 F.), or are heated above the temperature at which pyrolysis occurs (at about 340xc2x0 C. or 644xc2x0 F.), there is typically an induction period before deposition of carbon rich materials occurs. This induction period can be variable, ranging from a few seconds to hours, depending on the particular hydrocarbon material and the temperature at which it is processed. To avoid deposition of carbon rich material refiners often process hydrocarbon materials based on arbitrary criteria Because arbitrary criteria are used, conventional processing of hydrocarbon materials can result in product yields that may not be maximal.
Because of the substantial benefits that can result from predicting if, when, or to what degree particular processing parameters may induce hydrocarbon materials to form heterogeneous mixtures; there has been extensive commercial interest in technology to define indicia of stability with respect to the homogeneous mixture, or to define thresholds of instability at which transition to the heterogeneous mixture may occur. Such indica of stability or thresholds of instability for hydrocarbon materials may be used, for example, to evaluate the suitability of hydrocarbon materials for particular types of processing, to predict the proximity to carbon deposition or coke formation, or for controlling hydrocarbon material processing in a manner which eliminates, minimizes, or predicts the amount of carbon deposition or coke formation. Even though commercial interest has generated substantial research in various fields, a long felt but unresolved need remains for methods of determining when hydrocarbon materials comprise homogeneous mixtures, or for development of indicia of stability for such homogenous mixtures, or for more objective thresholds of instability for such homogenous mixtures to assist in predicting proximity to formation of heterogeneous mixtures. See for example, U.S. Pat. No. 5,853,565, hereby incorporated by reference. As such, substantial problems with respect to the evaluation of hydrocarbon materials for processing, or to the processing of hydrocarbon materials, remained unresolved.
A significant problem with conventional technology for the evaluation and processing of hydrocarbon material may be the failure of conventional technology to define, provide measures for, or interpretations of, the dynamics of unimodal characteristics of intact hydrocarbon materials. Unimodal characteristics define a comprehensible pattern of attributes having predictable variation to changing environmental or processing parameters. As such, unimodal characteristics make possible the development of ascertainable indicia for comparative evaluation of the functionally related components that make up a hydrocarbon material. Ascertainable indicia can make the response of hydrocarbon materials to such environmental or processing parameters predictable. Unimodal characteristics may also provide objective indica for the manufacture of hydrocarbon material products to assure that components have an anticipated degree of association. As can be understood, conventional technology has focused upon evaluation of the characteristics of separated components of hydrocarbon materials. The data obtained by evaluation of these isolated components is then typically used to determine the differences between types of hydrocarbon materials. However, conventional evaluation of isolated components does not provide a substantial amount of information about the intact hydrocarbon material itself. It can be understood that while conventional technology may understand that a hydrocarbon materials can be made up of chemical components, or that conventional technology may understand that the chemical components have a certain physical relationship or distribution with respect to one another, conventional technology may provide, if at all, only a limited insight about the dynamic behavior of the various components of a hydrocarbon materials to changing environmental or processing parameters, or how the components functionally relate to maintain the stability of their physical association. As such, conventional technology may not provide suitable indica of stability, thresholds of instability, or the methods for comparing such indicia of stability to such thresholds of instability which are the ascertainable measures of the unimodal characteristics of intact, unseparated hydrocarbon material. Indeed, conventional technology affords few, if any, tools for diagnosing or predicting how a hydrocarbon material will behave under a specific set of circumstances.
Another significant problem with conventional technology for the evaluation and processing of hydrocarbon material may be formation of carbon rich material during non-pyrolytic events (at or below about 340xc2x0 C.). The deposition of carbon rich material, such as coke, can result in fouling of heat exchange devices, or other refinery equipment in both upstream and downstream operations. This equipment may have to be shut down for mechanical coke removal as disclosed by Schabron, J. F. et al., Deposition From Heavy Oils, pp. viii and 2, (2000), hereby incorporated by reference.
Another significant problem with conventional technology for the evaluation and processing of hydrocarbon material may also be the formation of carbon rich deposits, such as coke, from pyrolytic events (at or above about 340xc2x0 C.). Deposition of carbon rich material, such as coke, from pyrolytic events during processing can also result in the problems described above including having to shut down processing equipment for mechanical removal of the deposited materials.
Another significant problem with conventional technology for the evaluation and processing of hydrocarbon material may be the lack of a method or use of arbitrary criteria for predicting the proximity of a hydrocarbon material to the point of transition from a homogenous mixture of components to a heterogeneous mixture of components, including the proximity to carbon deposition or coke formation.
Another significant problem with conventional technology for the evaluation and processing of hydrocarbon material may be a low yield of liquid distillates. The use of arbitrary criteria to assess the stability of a homogeneous mixture of hydrocarbon materials, or to predict when carbon deposition may occur, can result in distillation parameters for the hydrocarbon material that stop the distillation sooner than need be to avoid deposition of carbon rich materials, such as coke. When distillation is stopped sooner than is necessary to avoid carbon deposition, it can result in less than maximal product yield from the hydrocarbon material. In 1997, for example, the average United States atmospheric and vacuum distillation refinery capacity was about 23 million barrels per day as disclosed by the Department of Energy, OIT Report, p. 5, (1998), hereby incorporated by reference. Solvent deasphalting capacity was about 0.3 million barrels per day. About 1.8 million barrels per day of heavy end feedstocks produced in 1997 from atmospheric and vacuum distillation columns and solvent-deasphalting units were input to thermal cracking and coking operations. This represents about 10% of the crude run. Id. at p. 49. An additional 6.5 million barrels per day went into catalytic cracking and hydrotreating units. Based on the total of 1.8 million barrels of total heavy ends minus about 0.3 million from solvent deasphalting, about 1.5 million barrels of heavy ends per day of thermal cracking and coking feed are produced from distillation operations. Assuming a one percent increase in United States distillate output because of efficiency improvements, an increase of about 15,000 average barrels per day of distillate and a corresponding reduction of heavy ends would result. Efficiency increases well above 1% could be possible if the proximity to carbon deposition or coking for a hydrocarbon material could be measured.
Another significant problem with conventional technology for the evaluation and processing of hydrocarbon material may be the inefficient use of energy. Coking operations use about 166,000-258,000 Btu per barrel of hydrocarbon material fees Department of Energy, OIT Report, pp. 62-63, (1998). Hydrotreater energy use is comparable, and a similar consideration may apply. Since most of the energy used can be to initially heat all of the hydrocarbon feed material for distillation, there may be only minimal extra heat required to obtain a 1% improvement of distillate output at a particular temperature. For each 1% decrease in hydrocarbon material feed, there would be a potential savings of about 2.5-3.9 billion Btu with respect to hydrocarbon materials that do not need to be heated for coking, since they will have been recovered in an optimized distillate stream.
Another significant problem with conventional technology for the evaluation and processing of hydrocarbon material may be high emissions. An energy savings of about 2.5-3.9 billion Btu per day, as discussed above, can result in a corresponding lowering of emissions from fuel that is not burned in processing operations. For example, residual fuel used as the heat source produces about 174 pounds of carbon dioxide per million Btu generated Department of Energy, OIT Report, pp. 27, (1998). Thus, in the U.S., the reduction in carbon dioxide emissions for each 1% industry-wide efficiency improvement may be about 218-679 tons per day!
Another significant problem with conventional technology for the evaluation and processing of hydrocarbon material may be financial losses. The disruption of hydrocarbon material processing from fouling due to deposition of carbon rich material, such as coke, is pervasive throughout the industry. The financial losses due to unscheduled downtime events as a result of non-pyrolytic, or of pyrolytic, deposition of carbon rich materials such as coke, may be difficult to quantify, but they are important.
Another significant problem with conventional technology for the evaluation and processing of hydrocarbon material may be that the liquid products of distillation may be of lower quality. Interrupting the distillation process, or proceeding with the distillation process in steps or stages, to avoid deposition of carbon rich materials or coke may allow for contamination of the liquid distillates.
Yet another significant problem with existing methods of processing hydrocarbon materials may be lack of a method for predicting the amount of initial deposition of carbon rich material or coke formation upon pyrolysis of a hydrocarbon material.
Still another significant problem with existing methods of processing of hydrocarbon materials may be the lack of apparatus or methods that are practical, convenient, or provide for real time data with respect to the stability of hydrocarbon materials.
With respect to processing hydrocarbon materials in general and specifically with respect to characterizing the dynamics of unseparated, intact hydrocarbon materials including predicting proximity to carbon deposition or coke formation, it can be understood there exists an array of problems which have remained unresolved by use of conventional hydrocarbon processing technology. The present invention addresses each of the above-mentioned problems and provides practical solutions.
Indica which define unimodal characteristics of hydrocarbon materials, or indicia which estimate the stability of such unimodal characteristics of hydrocarbon materials which may be used separately or may be used in combination, or may be u in comparison to determined threshold of instability for such unimodal characteristics, to assist in determining the proximity of such unimodal characteristics to formation of multimodal characteristics, or to assist in predicting the degree of acquired multimodal characteristics in response to various processing parameters.
Naturally, as a result of these several different and potentially independent aspects of the invention, the objects of the invention are quite varied.
A broad object of a particular embodiment of the invention can be to establish values for various associations between components of a hydrocarbon material which define the attributes or characteristics of a unimodal system. One aspect of this object can be to provide a value for the size of a core material in comparison to the size of the core material having sufficient solvent salvation shell to maintain unimodal character (Ks) A second aspect of this object can be to provide an average value for the relative size ratio of a plurality of solvated core materials and the size of the plurality of solvated core materials having sufficient associated solvent (for example trapped solvent between them) to maintain unimodal character (KF). A third aspect of this object can be to provide a value for the solvation shell and associated solvent about a core particle or plurality of core particles to maintain unimodal characteristics (K) where K=KSxc2x7KF.
A second broad object of a particular embodiment of the invention can be to provide indicia of stability for the above-mentioned unimodal characteristics exhibited by hydrocarbon materials. Indicia of stability are values that result from measuring the degree of association between certain components in the hydrocarbon material which can allow assessment of the stability of a unimodal characteristic at a given point in time. Having objective values that reflect the instant degree of stability of the unimodal characteristics can be useful in evaluating suitability of hydrocarbon materials for various types of processing parameters, or for maintenance of unimodal characteristics during hydrocarbon processing.
Another broad object of a particular embodiment of the invention can be to establish thresholds of instability. A threshold of instability establishes a degree of association (or lack of association) between components of a hydrocarbon material at which acquisition of multimodal characteristics by the hydrocarbon material may be expected. These thresholds of instability may be used in conjunction with the above-mentioned indica of stability to assess the proximity of hydrocarbon materials having unimodal characteristics to the threshold of instability or to acquisition of multimodal characteristics.
Another object of a particular embodiment of the invention can be to provide indicia of stability or to establish thresholds of instability based upon instrumented measurement of various size ratios which correlate with unimodal characteristics. The size ratio of the core material to the core material with associated solvent (KS), or the ratio of an average size of a plurality of solvated core materials with an associated solvent to an average size of a plurality of solvated core materials, thus representing an amount of associated solvent associated with a plurality of solvated core materials (KF), or the solvation shell about a core particle or plurality of core particles (K) where K=Ksxc2x7KF, independently or in combination can be useful in measuring unimodal character of a hydrocarbon material. These size relationships may be evaluated by the use of various instrumented techniques such as nuclear magnetic resonance spectroscopy, nuclear magnetic resonance tomography, mass spectrometry, infrared spectrometry, raman spectroscopy, size exclusion chromatography, gel electrophoresis device, and paper chromatography.
Another object of a particular embodiment of the invention can be to provide indicia of stability related to the molecular weight of particular components in a hydrocarbon material which correlate with the stability of unimodal characteristics.
Another object of a particular embodiment of the invention can be to provide indicia of stability based upon the distribution of various polar components in hydrocarbon materials. One aspect of this embodiment of the invention may be an indicia of stability determined as the amount of asphaltenes soluble in particular solvent having a particular polarity. Of course, the tern xe2x80x9camountxe2x80x9d generally, may include any of different kinds of measurements such as, but not limited to, quantities, lengths, sizes, volumes, weights, weight percentages, weight fractions, volume percentages, volume fractions, radii, diameters, circumferences, or the like, however measured such as but certainly not limited to ultrasound spectroscopy, microscopy, filtration, solvation, titration, NMR spectroscopy, NMR tomography, mass spectrometry, infrared spectrometry, infrared Raman spectroscopy, size exclusion chromatography, gel electrophoresis, paper chromatography, or the like. For example, the amount of asphaltenes precipitated with heptane soluble in cyclohexane can be diagnostic of the stability of the unimodal character of hydrocarbon materials. A second aspect of this embodiment of the invention can be an indicia of stability determined as the ratio of the weight percent of solvent soluble asphaltenes to the weight percent asphaltenes that are not solvent soluble. For example, the ratio of the weight percent of the cyclohexane soluble portion of the heptane precipitated asphaltenes to the weight per cent of the heptane precipitated asphaltenes appears to provide a sensitive indicator of stability of the unimodal character of hydrocarbon materials. A third aspect of this embodiment of the invention can be an indicia of stability based upon titration data. This involves the a titration of solutions of hydrocarbon material with a weak solvent to the point of asphaltene precipitation. An indicia of stability can be described based on the titration data defined as pa/Cmin.
Another object of a particular embodiment of the invention can be to use the determined indicia of stability in comparison to the established thresholds of instability to assess the proximity of unimodal characteristics to the threshold of instability. One aspect of this object of the invention can be to predict the proximity of a hydrocarbon material to coke formation.
Another object of a particular embodiment of the invention can be to use the indicia of stability, individually or in combination to evaluate hydrocarbon materials prior to processing or during processing to model substantially continuous distillation parameters for a particular hydrocarbon material or mixture hydrocarbon materials.
Another object of a particular embodiment of the invention can be optimization of the yields of distillable liquids from a hydrocarbon material having unimodal characteristics. Any increase in the yield of distillable liquids from the same amount of hydrocarbon material such as heavy oil or petroleum residuum provides an immediate increase in revenue. As such, a method of optimizing yields of distillable liquids has immediate and important commercial applications.
Another object of a particular embodiment of the invention can be to predict the degree of multimodal characteristics that may be acquired by a particular hydrocarbon material with respect to various processing parameters. One aspect of this object may be to predict the initial amount of carbon rich material, such as coke, that may be formed upon processing of a hydrocarbon material with particular processing parameters.
Another object of a particular embodiment of the invention can be to save energy. There may be a significant energy savings involved when a higher yield of distillates is produced from the same amount of hydrocarbon material. As described above, there may be only a minimal amount of extra heat required for a 1% improvement of distillate output at a particular temperature since the majority of the energy is used to initially heat all the hydrocarbon material for distillation. For each 1% decrease in the amount of distillate bottoms heated for a subsequent coking operation in the United States a potential savings in energy of about 2.5 billion Btu to about 3.9 billion Btu per day may be realized.
Another object of a particular embodiment of the invention can be to reduce emissions. The above-mentioned potential savings in energy of about 2.5 billion Btu to about 3.9 billion Btu results in a corresponding reduction in emissions from fuel that is not burned in processing additional hydrocarbon material. For example, residual fuel used to as the heat source for processing produces about 174 pounds of carbon dioxide per million Btu generated. Department of Energy, QIT Report, p. 27 (1998), hereby incorporated by reference. Thus in the United States, the reduction in carbon dioxide emission for each 1% industry-wide efficiency improvement is about 218-679 tons.
Another object of a particular embodiment of the invention can be to produce higher initial quality as compared to conventional liquid distillables. Because the process of distillation may be nearly continuous, the distillates may have fewer opportunities to collect water and become otherwise contaminated. This may result in higher purity distillates and perhaps lower post distillation processing costs. As such, distillates from near continuous distillation processes made possible from the instant invention may be distinguishable from conventional distillation products.
Still another object of a particular embodiment of the invention can be to provide a molecular weight/polarity map system to assess the solubility of various components in a mixture of asphaltene complexes at various distillation parameters. Such a map system may provide an evaluation method for diagnosing processing conditions for hydrocarbon materials having unimodal characteristics prior to or during distillation.
Yet another object of a particular embodiment of the invention can be to establish a sequential solvent extraction system to isolate various asphaltene complexes from hydrocarbon materials having unimodal characteristics based on molecular weight or polarity.
Naturally further objects of the invention may be disclosed throughout other areas of the specification and claims.